1. Field of the Invention
The present invention relates to industrial automation systems comprising automation devices interconnected with one another via an industrial communication network and, more particularly, to a communication device and method for providing a name service within an industrial automation system.
2. Description of the Related Art
Generally, an industrial automation system comprises a multiplicity of automation devices interconnected with one another via an industrial communication network, and is typically used to control or regulate plants, machines or devices as part of a production or process automation. Due to time-critical boundary conditions in technical systems automated via industrial automation systems, real-time communication protocols, such as PROFINET, PROFIBUS or real-time-Ethernet, are mainly used for communication between automation devices in industrial communication networks.
Interruptions of communication links between computer units of an industrial automation system or automation devices can lead to an unwanted or unnecessary repetition of a transmission of a service request. This repetition causes additional loading on communication links of the industrial automation system that can lead to further system disturbances or errors. A particular set of problems in industrial automation systems regularly results from message traffic with relatively many but relatively short messages as a result of which the above problems are intensified.
Due to a utilization for frequently extremely different applications, problems can arise in Ethernet-based communication networks, for example, when network resources are claimed for a transmission of short data frames competing with real-time requirements for a transmission of data frames having a large content of useful data. This can lead to a delayed transmission of the data frames with real-time requirements or even to a loss of individual ones of such data frames.
WO 2007/144364 A1 describes a method for networking an automated plant that comprises at least one cell with a subnetwork. The subnetwork is connected via a router to a further subnetwork of the automated plant. To network the automated plant, a multicast group is provided that extends over both subnetworks. By means of the multicast group, a communication network address of a communication network interface of an assembly is detected. In this context, the assembly has joined the multicast group previously via the communication network address and the communication network interface has been connected previously to the subnetwork. Via the communication network address, a name is assigned to the communication network interface of the assembly. In a further step, a further communication network address of the communication network interface of the assembly is determined which exhibits at least a part of a numeric representation of the name.
U.S. Pat. No. 8,194,661 B2 discloses a method for the automatic configuration of a communication device within a segmented communication network in which a monitoring unit checks whether a received IPv6 data packet comprises a router advertisement or a router solicitation. In the case of a router solicitation, a MAC sender address of the data packet is removed from the IPv6 data packet by the monitoring unit. In addition, the monitoring unit inserts an external MAC address into the IPv6 data packet in order to forward the latter as a multicast message to a router. In the case of a router advertisement, the monitoring unit removes a MAC router address from the IPv6 data packet and inserts instead an internal MAC address into the IPv6 data packet in order to forward the latter as a unicast message to the communication device to be configured.
European patent application EP 14166194.2 relates to a method for configuring a communication device within an industrial automation system in which a configuration unit of the communication device transmits a datagram with a configuration request to a configuration server. Following the configuration request, the configuration server assigns to the communication device at least a first topological device name component that is allocated to a spatial or hierarchical arrangement of the configuration server. Each forwarding distributor unit adds a further topological device name component that is allocated to a spatial or hierarchical arrangement of the respective forwarding distributor unit. The configuration unit of the communication device generates from the topological device name components and a name component unambiguous within its subnetwork its device name.
European patent application EP 14166376.5 discloses a method for providing a name service within an industrial communication system in which IPv6 prefixes are distributed by routers via messages with router advertisements in respective lower-level subnetworks. In this context, the router advertisements comprise a topological or hierarchical name component of the respective router that is allocated to a spatial or hierarchical arrangement of the respective router. Router advertisements with name information from higher-level subnetworks are received by routers allocated to lower-level subnetworks and supplemented by a topological or hierarchical name component allocated to the respective router and distributed within the respective lower-level subnetwork. Communication terminals independently generate their device name from topological or hierarchical name components and a name component which is unambiguous within their respective subnetwork.
From European patent application EP15162021.8, it is known that a name service server of an industrial automation system for providing a name service sends out messages with router advertisements that comprise information on an IPv6 address of the name service server. Communication terminals generate their IPv6 address independently from IPv6 prefixes distributed within their respective subnetwork via router advertisements. In addition, communication terminals generate their device name independently from topological or hierarchical name components and a name component unambiguous within their respective subnetwork. Communication devices each comprise a name service client for dynamic DNS (Domain Name System) by which storage of an IPv6 address and an associated device name of the respective communication device is requested in the name service server via the IPv6 address of the name service server.